Brake warning light: what it means and when to stop

The brake warning light is red and usually shows an exclamation mark inside a circle, sometimes with brackets either side, or the word "BRAKE". On many cars the same light does several jobs: it shows the handbrake (parking brake) is on, warns of low brake fluid, and on some cars flags a brake system fault. Some cars have a separate amber light for worn pads. Check your owner's manual for what each symbol means on your car.

First, check the handbrake

If the light came on as you set off, make sure the handbrake or electronic parking brake is fully released. If the light goes out, that was all it was. If it stays on with the handbrake fully off, or comes on while you are driving, treat it as a brake problem.

When to stop driving

Stop somewhere safe as soon as you can, keep your speed low and avoid sudden braking, if:

• the light stays on with the handbrake fully off,
• the brake pedal feels soft or spongy, or goes down further than usual,
• the ABS light is on at the same time,
• you hear grinding, or the car pulls to one side when you brake.

The AA's advice: if you need to press the pedal further than usual, the hydraulic brake circuits may have failed, so pull over and get help. Do not drive on to "see if it clears". Call your breakdown service or a mobile mechanic.

If the fluid level turns out to be fine and the pedal feels completely normal, the AA says it may be a sensor fault and it is safe to drive carefully to a garage.

Likely causes, most common first

1. Handbrake or parking brake still on

   The harmless one. The light goes out as soon as the brake is fully released. If it stays on even then, the handbrake switch or cable adjustment may be at fault.

2. Brake fluid low because the pads are worn

   As pads wear, the caliper pistons move further out and hold more fluid, so the level in the reservoir drops. A low level with no leak often means the pads are nearly finished.

   Read the fix guide →

3. Brake fluid leak

   A leaking brake pipe, hose, caliper or master cylinder lets fluid escape. Look for damp patches near the wheels or under the car. A leak is dangerous: the brakes can lose power suddenly.

4. Faulty fluid level sensor or wiring

   The float sensor in the reservoir or its wiring can fail and turn the light on even though the level is fine.

5. Brake system or ABS fault

   On many modern cars, faults in the electronic brake force system also turn this light on, often together with the ABS light. Stop and get help.

   Read the fix guide →

How to check the brake fluid level

Only do this with the car parked on level ground and the engine off. The reservoir is usually a small translucent plastic tank near the back of the engine bay, with "MIN" and "MAX" marks and a cap showing the brake symbol. Your owner's manual shows where it is.

1. Look at the level against the marks without opening the cap.
2. If it is below MIN, do not drive. Even if you top it up, the reason it dropped is still there.
3. Brake fluid damages paint and irritates skin and eyes, so if you do top up, use only the type in your manual and wipe up spills straight away.

DIY or garage?

How to prevent it

• Have the pads checked at every service, so they never get low enough to drag the fluid level down.
• Have the brake fluid changed at the interval in your owner's manual.
• Glance at the fluid reservoir when you check your oil.
• Never ignore a soft pedal or a light that flickers on and off: get it checked early.

In the UK, an illuminated brake fluid warning light is recorded as a minor defect at the MOT, but the underlying fault is what matters for your safety.